Telomerization in an aqueous medium using water-soluble monomers and water-insoluble telogens is known. For example, U.S. Pat. No. 3,665,035 discloses the telomerization of acrylic acid with mercaptoethanol or thioglycolic acid. Also known is the telomerization of water-soluble monomers such as acrylic acid and water-insoluble telogens such as dodecyl mercaptan in an organic solvent in which all the reactants are soluble. The polymers produced may be insoluble in the solvent that is used, in which case a precipitation polymerization takes place.
Although telomers with molecular weights adjustable within broad limits can be prepared by the telomerization of water-soluble monomers and water-insoluble telogens in an aqueous medium, such adjustability is limited to processes where the telogens that are initially water-insoluble are completely soluble in water at the polymerization temperature. The controlled introduction of a long-chain telogen radical, which is needed for many applications, is not successful in such a procedure. In addition, it has not been successful to add water-insoluble telogens in powdered form, as an emulsion or suspension, to aqueous monomer solutions.
The telomerization of water-soluble monomers with water-insoluble telogens in an organic solvent is suitable in principle. However, working in organic solvents necessitates special technical precautions during the procedure. In addition, the solvent interfers with important applications of the telomers produced, such as, for example, when the telomers are used as surfactants. Consequently, the products must be isolated by precipitation or distillation of the solvent and again dissolved in water before their application. This means additional work with some products.